Modal identification of Shanghai World Financial Center both from free and ambient vibration response

Abstract

The Shanghai World Financial Center (SWFC), a currently built super high-rise building, is located in Lujiazui area. The height of this 101-storey building is 492m above ground. A set of dynamic field tests were conducted on the building from April to May 2008. To identify the dynamic properties of the building, three output-only modal identification techniques are applied to the ambient and forced vibration measurements. These methods consist of: the Peak-Picking method (PP) combined with the half-power bandwidth method, the Random Decrement based method (RDT) combined with curve-fitting method, and the Hilbert–Huang transform method (HHT). The fundamental frequencies and damping ratios in two translational directions are identified from the free decays of forced vibration tests. The estimated eleven modal frequencies and damping ratios under microtremors from the Peaking-Picking method and the Hilbert–Huang transform method are compared to each other with favorable correlation. The modal frequencies from the finite element analysis and the shaking table test are further studied with the results of field test. The effect of the installed Active Tuned Mass Damper (ATMD) on the damping characteristics of the building is presented. Based on the identified results, accuracy and efficiency of these methods are investigated with the length of Fast-Fourier Transform and the effect of RDT. The modal properties of the SWFC presented in this paper can be used as baseline in future health monitoring.